For vertically stacked wells undergoing hydraulic fracture stimulation, the order in which wells are stimulated can affect the achieved fracture length, width, height and intensity. We examine the effect of stimulation order for the plug-and-perf completion of two pairs of vertically stacked wells in the Marcellus Shale. Each pair of lateral wells hosts one well targeting the Lower Marcellus Formation, and one well targeting the Upper Marcellus Formation. All stages are completed in one well before moving to the next. For one pair of laterals, the Lower Marcellus is simulated before the Upper Marcellus. In this case, the cumulative seismic moment, and by extension the reservoir deformation, is much greater for the well which is completed second. In the next pair of laterals the stimulation order reverses and the Upper Marcellus Formation is stimulated before the Lower Marcellus. In this case, the cumulative seismic moment, and by extension total reservoir deformation, is again much greater for the well that is completed second. For the wells targeting both the Upper and Lower Marcellus, the achieved fracture length and width is independent of which Formation is simulated first. However, for both formations the kurtosis of the depth distribution is greater for whichever Formation is stimulated second. These observations demonstrate that in situ stress changes induced by hydraulic fracturing effect achieved fracture length and fracture intensity in the Marcellus Formation.